IMAP: fix 209, use isEqualTo instead of contains to search keywords on Exchange 2010

git-svn-id: http://svn.code.sf.net/p/davmail/code/trunk@2283 3d1905a2-6b24-0410-a738-b14d5a86fcbd

src/java/davmail/imap/ImapConnection.java

@@ -1343,7 +1343,7 @@ public class ImapConnection extends AbstractConnection {
                     session.contains("to", value),
                     session.contains("cc", value));
         } else if ("KEYWORD".equals(token)) {
-            return session.contains("keywords", session.convertFlagToKeyword(tokens.nextToken()));
+            return session.isEqualTo("keywords", session.convertFlagToKeyword(tokens.nextToken()));
         } else if ("FROM".equals(token)) {
             return session.contains("from", tokens.nextToken());
         } else if ("TO".equals(token)) {